Hi Guys I am redoing everything and i took my SLP runners and my stock plenum and center head up to my guys who are going to port, polish and gasket match them all together.

My problem is that my buddy says he doesn't understand why i want to cut the inside of the center head to siamese it like it is done by some guys here on the thirdgen. He says it may not flow better. what I want to know is this correct I know some guys have siamesed their center head.......is it worth the time and $$$$.

regards,
Jamie

 

I siamesed my plenum chamber. However my SLP runners are also siamesed. I don't know if yours are siamesed. If they are I would siamese the plenum. If they are not I don't know how much difference it will make. Port matching will help. I would also get a bigger intake manifold such as the Edelbrock.

I have the early SLP runners where one side of the runner is fulley siamesed from one end to the other and the other side is partially siamesed and at the top only. The car is apart now at Dyno Don's for mods and I will have him siamese the other runner at the bottom by the intake manifold. Allen

 

Center head = intake manifold, I'm assuming?

From what we've seen here, siamesing that a bit allows the engine to breath better - or to get more air at higher rpm, which tpi engines need help with. Do a search here and you'll probably find a post by Ed Maher from a while back.

 

If you dont port the intake manifold with the runners and plenum you may not see much of a gain at all. The stock manifold is only good to 4500rpms, then it flatlines. Either get another one or port and match the one you have. Is it worth it? Check out some prices on some other high flowing cfm manifolds and decide for yourself. Open the intake and let the engine breath.....

 

Thanks for the information guys. I am going to port match it all. I am just wondering if it is really necessary to siamese the intake manifold? If it helps or hurts.

thanks,
Jamie

 

Personally I would not siamese the intake manifold I have not heard the best of stories from doing this. But your not going to be happy spending all that cash on trying to port your stock manifold, you really need to go with an afteramarket so you can really port it out. See the difference.

 

The picture before I had to hold the golf ball to the hole because it would not even rest on the ledge of the port. Now this is a ported Edelbrock. See the difference in just material to port out and work with. Now the ball goes right in.